Treatment of regenerated cellulose fabrics with urea-alkali-stannate solution



Patented Oct. 24, l 950 TREATMENT OF REGENERATED CELLULOSE FABRICS WITH UREA-ALKALI-STANNATE SOLUTION Charles L. Mantell, Manhassct, and Theodore J. Dabrowski, Kew Gardens, N. Y., asslgnors to United Merchants & Manufacturers, Inc., Wilmington, Del., a corporation of Delaware No Drawing. Application May 10, 1949,

Serial No. 92,513

(c1. s-uaz) 19 Claims.

This invention relates to the treatment of regenerated cellulose fabric and has for its primary object a method of modifying the normal char acteristics of spun and/or filament regenerated cellulose goods to the end of producing a fabric of enhanced value and utility, the method requiring no complicated or special equipment for its practice and being otherwise economical to carry out. As hereinafter described in greater detail, the invention contemplates the treatment of the fabric with a, solution which, in more or less noticeable degree according to the character of the fabric and the method employed, produces some or all ofthe effects of modifying the shrinkage characteristics-9f the fabric, rendering the fabric stiffer and' soffnewhat translucent, and, in the case of spunareigenerated c'ellulose goods, eliminating fuzz.

The invention essentially comprises a process of treating regenerated cellulose fabric with a solution containing caustic stannate and urea, hereinafter referred toas the treating solution, there being obtained a fabric having, among other effects, appreciably modified shrinkage characteristics; that is, it shows a substantially reduced shrinkage by comparison with the normal shrinkage of the untreated fabric, considering such normal shrinkage to be the initial wash shrinkage. In addition, in the case of spun r'egenerated cellulose, the treated fabric has a more clear-cut and attractive appearance. Thus, when the untreated fabric is held up to the light and examined, i. e., held between the light and the eye, it presents a misty appearance due to the lack of sharp definition of the warp and weft thread outlines which results from the fuzz on the threads. This characteristic is particularly evident when such fabrics are used, for example, as curtains. It has been found, according to this invention, that if the fabric is treated as described, its appearance is quite radically changed. When a fabric so treated is held up to the light and examined as before, it is observed that the threads are sharply outlined, there being substantially no evidence of fuzz. It has also been observed in some instances that, notwithstanding the sharpening of the outlines of the threads, the body of each thread assumes a somewhat translucent character. As will be understood, these last-mentioned effects will each be more or less noticeable and of varying practical consequence depending on the character of the fabric and the use to which it is put; but, for convenience, they may be described as bringing about a clarification of the fabric.

It has further been observed that the treated fabric tends to become stiffer by comparison with the untreated fabric. 4 This characteristic of stiffness is highly desirable in certain materials, for example, in curtain and table goods and in certain types of dresses and blouses, e. g., lawns and organdies.

As described, the treating solution may be composed of caustic stannate and urea. It may be prepared by mixing together an aqueous solution of urea and an alkali metal stannate selected from the class consisting of sodium stannate and potassium stannate; or by adding hydrated or precipitated stannic oxide to an aqueous solution of an alkali metal hydroxide selected from the class consisting of sodium hydroxide and potassium hydroxide, sodium stannate and potassium stannate respectively being formed, and then incorporating 'the urea. It is to be understood that in referring to the stannic oxide content of the solution, it is intended to include, the oxide added as such or as comprised in the alkali metal stannate added to the solution or formed therein. Compounds which, when added to a caustic stannate solution, hydrolyze to form urea, may be used in making up the solvent. Such compounds may include, for examples, cyanamide, guanidine, guanylurea, etc. In the premises, it will be understood that the term urea as used herein is intended to include urea per se and also compounds which produce urea as in theforegoing manner. Moreover, in place of the urea per se or the urea forming compounds as described, other compounds may be employed as one of the com-v ponents in the present treating solution as, for examples, the alkali metal thiocyanates; sodium thiocyanate, potassium thiocyanate or ammonium thiocyanate, and the polyamines; ethylene diamine or hexamethylene tetramine. The amount of urea generally used is about 1 to about 15% by weight, preferably about 10 to'l5%. Stannic oxide, whether added as such or in the form of the stannate, may be present in amounts ranging from about 1 to about 2% by weight. Preferably, it is added in the form of sodium stannate (technical grade, 44% as $102), in amounts ranging from about 2 to about 4% by weight. The caustic may be varied from about 9 to 18% by weight, or more, although the use of higher concentrations of caustic generally does not justify the added expense involved. If sodium hydroxide is employed as the caustic, a preferred concentration is from about 9 to about 13%; for potassium hydroxide a preferred range is from about 12 to about 18%. In general, as

asamss centrations, there is no worthwhile improvement in results. A preferred solution is one containing about urea, about 1.5% stannic oxide,

' and about 11% caustic.

The weight relations of the sodium stannate referred to in the examples following are based on the commercial material known as sodium stannate which contains about 44% of 8110:, rather than on the compound represented by the formula NaaSnOa. Material of other concentrations of SnOa may, of course, be employed, care being had to maintain an overall amount of 8110: of between about 1% and about 2%.

In treating regenerated cellulose fabric or fabric containing such regenerated cellulose, according to the present invention, the solution may be applied simplyby immersing the fabric in the solution, although any other suitable method may be employed as, for examples, by pouring the solution on the material or by padding or rollers. The fabric may or may not .be under tension during the application of the solution. The time of treatment may range from about 10 seconds to about 90 seconds. preferably from about 10 seconds to about 1 'minute, this being known as the act on time of the solution. It extends from the point at which the material is put into the solution or otherwise brought into contact therewith, until it is flushed of thesame. The fabric, of course, is actually immersed in the solution for a lesser interval than the action time or for a period from about 1 second up to about 85 seconds. Treating temperatures may range from about 68 to about 90 F. although higher and lower temperatures, say from the freezing point to about 120 F., may be employed. After immersion the fabric is preferably, but not necessarily, squeezed and framed to a desired width, for example, on a tenter frame. At the end of the solution action time the fabric is adequately flushed, preferably with hot water or a dilute solution of sulfuric acid, acetic acid, sodium bicarbonate or other suitable neutralizing agent to neutralize the fabric and set the yarns at the crossing points in the goods. Thereafter the material may be dried, preferably at an elevated temperature by means of hot air. It is desirable, but not essential, that the flushing or neutralizing steps and the drying take place while the goods are framed to the desired width. Better results are obtained when the material is held under tension during these steps of the procedure. The following examples illustrate the method and results obtained in controlling the shrinkage of regenerated cellulose material:

Example 1 Spun rayon marquisette was run through a solution made from about 9% sodium hydroxide,

according to the procedure given in Federal Specification for Textiles; General Specifications,

Test Methods, 0. C. C.-T-l91a (page 17, section 3). The resultsareasfollows: Y

Warp Filling Original Cloth, Per cent 10,3 ll. 9

Treated Cloth, Per cent 2. 8 2.3

Example 2 A number of solutions of varying urea concentration were made up and the shrinkage of rayon marquisette determined for each solution. The procedure of Example 1 was employed in each case. Following are the results:

Shrinkage Per Cent Warp Filling Original cloth l9. 6 16. 6 Treated cloth:

Sodium NaOH Urea, Per Cent $333? I! Cent In the foregoing examples the visual characteristics of the treated cloth are appreciably altered. By comparison with the original material, the treated cloth has a cleaner thread outline and an overall translucent appearance. These effects are produced in addition to the effect of shrinkage or dimensional stability. The following example shows with greater particularity the stiffness and translucency effects obtainable by the invention:

Example 3 Following are the data obtained:

Solution Composition Stiffness Transluoency Run No.

NaOH, misnoi, Urea, mm Per Cent Per Cent 1: Cent 9 2 10 0.90 11 2 10 8) 13 2 10 8! moderate.

9 3 10 .70 ll 3 10 1.06 Do. 13 3 10 Do.

9 4 10 62 11 4 10 76 Do. 13 4 10 68 Do. 10 3 10 96 Do.

As will be observed, the stiffness effect is of a high order. The finish of the cloth treated as in the foregoing example, by which is included its 8 general clarified appearance, has been found to be permanent to washing. Cloth with this kind finish is especially desirable for sheer curtain materials, such as marquisettes, ninons, etc.

A practical application for producing translucency effects by this invention is in the making of simulated damask from regenerated cellulose fabrie. In this process the fabric is first printed in a suitable design with a resist gum paste, such as dextrine or British gum, and then passed in open width through the treating solution as described above. A preferred solution is one containing 10% sodium hydroxide, 1.5% stannic oxide, and 10% urea. After squeezing. the fabric'may be aired or allowed to pile up in a J-box or on a traveling belt for about $6 to about minutes, then framed to a desired width and washed and neutralized as described. After all the gum has been washed out of the goods they may be finished in the normal manner and framed out to width. If desired, an organic acid, e. g., acetic, prooionic. etc.. may be added to the sum or paste to aid in retarding the action of the treating solution on the resist-printed part .of the fabric.

This application is a continuation-in-part of oo-pending application Serial Number 1,054. filed January 7, 1948 now abandoned; the latter being a continuation-in-part of co-pending applicat on Serial Number 616 454, filed September 14, 1945 and now abandoned.

In the light of the foregoing description the following is claimed:

1. Process of modifying regenerated cellulose fabric which comprises treating said fabric with an aqueous solution comprising from about 1 to about 15% by weight of urea, an alkali metal stannate selected from the class consisting of sodium stannate and potassium stannate and equivalent to from about 1 to about 2% by weight of stannic oxide. and about 9 to about 18% by weight of an alkali metal hydroxide selected from the class consisting of sodium hydroxide and potassium hydroxide, for a time of treatment ranging from about seconds to about 1 minute. thereafter stretching the fabric, flushing said solution from the fabric and drying the same while in the stretched condition.

2. Process according to claim 1 in which the urea concentration of the solution is about 10 to about by weight.

3. Process according to claim 1 in which the urea concentration of the solution is about 10% by weight.

4. Process according to claim 1 in which the urea concentration of the solution is about 10% by weight, the stannic oxide about 1.5% by weight and the alkali metal hydroxide about 11% by weight.

5. Process according to claim 1 in which the alkali metal hydroxide is sodium hydroxide.

6. Process according to claim 2 in which the alkali metal hydroxide is sodium hydroxide.

'7. Process according to claim 3 in which the alkali metal hydroxide is sodium hydroxide.

8. Process according to claim 4 in which the alkali metal hydroxide is sodium hydroxide.

9. In the process of producing damask effects upon regenerated cellulose fabrics which comprises printing selected areas of the fabric with a resist gum paste and then subjecting the printed fabric to the action of a fabric treating agent, the improvement which comprises employing as the treating agent an aqueous solution comprisalkali metal stannate selected from the class consisting of sodium stannate and potassium stannate and equivalent to about 1 to about 2% by weight of stannic oxide, and about 9 to about 18% by weight of an alkali metal hydroxide selected from the classconsisting of sodium hydroxide and potassium hydroxide, treating the fabric with said solution for a time ranging from about 10 seconds to about 1 minute, thereafter stretching the fabric and washing and drying the same while in the stretched condition.

10. Process according to claim 9 in which the urea. concentration of the solution is about 10 to about 15% by weight.

11. Process according to claim 9 in which the urea concentration of the solution is about 10% by weight.

12. Process according to claim 9 in which the alkali metal hydroxide is sodium hydroxide.

13. Process according to claim 1 in which the alkali metal stannate is sodium stannate and in which the alkali metal hydroxide is sodium hydroxide.

14. Method of modifying fabric containing regenerated cellulose which comprises treating the fabric with an aqueous solution containing from about 1 to about 15% by weight of urea, sodium stannate equivalent to about 1 to about 2% by weight of stannic oxide, about 9 to about 13% by weight of sodium hydroxide, and the balance water, for a time ranging from about 10 seconds to about 90 seconds and thereafter stretching the. fabric and flushing the solution therefrom.

15. Method of modifying fabric containing regenerated cellulose which comprises treating the fabric with an aqueous solutionof from about 1 to about 15% by weight of urea, potassium stannate equivalent to about 1 to about 2% by weight of stannic oxide, about 12 to about 18% by weight of potassium hydroxide, and the balance water, for a time ranging from about 10 seconds to about 90 seconds and thereafter stretching the fabric and flushing the solution therefrom.

16. Process of inhibiting the wash shrinkage of fabric containing regenerated cellulose which comprises treating the fabric with an aqueous solution comprising from about 1 to about 15% by weight of urea. sodium stannate equivalent to from about 1 to about 2% by weight of stannic oxide, from about 9 to about 13% by weight of sodium hydroxide, and the balance water, for a time ranging from about 10 seconds to about 90 seconds and thereafter flushing the solution from the fabric and drying the same.

17. Method of modifying fabric containing regenerated cellulose which comprises treating the same with an aqueous solution of from about 1 to about 15% by weight of urea, sodium stannate equivalent to from about 1 to about 2% by weight of stannic oxide, from about 9 to about 18% by weight of sodium hydroxide, and the balance water, for a time ranging from about 10 seconds to about seconds and thereafter flushing the solution therefrom.

18. Method of modifying fabric containing regenerated cellulose which comprises treating the same with an aqueous solution of from about 1 to about 15% by weight of urea, potassium stannate equivalent to from about 1 to about 2% by weight of stannic oxide, from about 9 to about 18% of potassium hydroxide, and the balance water, for a time ranging from about 10 seconds to about 90 seconds, and thereafter flushing the solution therefrom.

I "19. Method of modifying fabric containing regenerated cellulose which comprises treating the same with an aqueous solution of from about 1 to about 15% by weight of urea, an alkali metal stannate selected from the class consisting of 5 sodium stannate and potassium stannate in an amount equivalent to from about 1 to about 2% by weight of stannic oxide, and from about 9 to about 18% by weight of an alkali metal hydroxide selected from the class consisting of sodium hydroxide and potassium hydroxide, and the balance water, for a time ranging from about 10 seconds to about 90 seconds and subsequently flushing the solution therefrom.

CHARLES L. THEODORE J. DABRJOWSKI.

a REFERENCES CITED The following references are of record in me of this patent: v

UNITED STATES PATENTS Number Name Date 1,630,385 Weber May a1, 1927 1,998,579 Heberlein Apr. 23, 1935 FOREIGN PATENTS Number Country Date 266,466 Great Britain Feb. 24, 1927 Great Britain Jan. 12, 1940 OTHER REFERENCES Katz et al., Rayon Text. Mo., Dec. 1940. PM! 54, 55. (Copy in Sci. Libi'.) 

1. PROCESS OF MODIFYING REGENERATED CELLULOSE FABRIC WHICH COMPRISES TREATING SAID FABRIC WITH AN AQUEOUS SOLUTION COMPRISING FROM ABOUT 1 TO ABOUT 15% BY WEIGHT OF UREA, AN ALKALI METAL STANNATE SELECTED FROM THE CLASS CONSISTING OF SODIUM STANNATE AND POTASSIUM STANNATE AND EQUIVALENT TO FROM ABOUT 1 TO ABOUT 2% BY WEIGHT OF STANNIC OXIDE, AND ABOUT 9 TO ABOUT 18% BY WEIGHT OF AN ALKALI METAL HYDROXIDE SELECTED FROM THE CLASS CONSISTING OF SODIUM HYDROXIDE AND POTASSIUM HYDROXIDE, FOR A TIME OF TREATMENT RANGING FROM ABOUT 10 SECONDS TO ABOUT 1 MINUTE, THEREAFTER STRETCHING THE FABRIC, FLUSHING SAID SOLUTION FROM THE FABRIC AND DRYING THE SAME WHILE IN THE STRETCHED CONDITION. 